Talk by Carlos Portera-Cailliau of UCLA. Given to the Redwood Center for Theoretical Neuroscience at UC Berkeley.
Subtle alterations in how cortical network dynamics are modulated by different behavioral states could disrupt normal brain function and underlie symptoms of neuropsychiatric disorders, including fragile X syndrome (FXS). Using two-photon calcium imaging and electrophysiology we recorded spontaneous neuronal ensemble activity in mouse somatosensory cortex. We find that unanesthetized Fmr1–/– mice exhibit abnormally high synchrony of neocortical network activity. Neuronal firing rates are also 3-fold higher in Fmr1–/– mice when the animals are in slow wave sleep or quiet wakefulness. Combined EEG/calcium imaging experiments confirmed that neurons in mutant mice have abnormally high firing and synchrony during sleep/rest. We conclude that cortical networks in FXS are hyperexcitable in a brain state-dependent manner during a critical period for experience-dependent plasticity. These state-dependent network defects could explain the intellectual, sleep and sensory integration dysfunctions associated with FXS.